With the Doctor cornered in the underground caves by androids, Adric ventures outside of the TARDIS and manages to destroy one of them. They get control of the situation and the Doctor manages to open the door they've located - but in doing so, he's activated a bomb. They set off to find who is behind it all and arrive on board a spaceship on its way to Earth. Unknown to them as yet is that it's all down to the Cybermen, who are determined to destroy the Earth. Written by
Did You Know?
Although the Cybermen refer to the events of "Tomb of the Cybermen" (1967) during the flashback sequence, the story was not extant in the archives at the time, so a clip from Doctor Who: The Wheel in Space: Episode 6
(1968) was used instead. See more
When the Doctor and Adric exit the TARDIS, the normal inside of the Police Public Call Box can be seen. See more
[regarding the inside of the TARDIS
It's bigger than you think.